Page:The American Cyclopædia (1879) Volume V.djvu/288

284 CONSUMPTION fingers " which are quite characteristic of this disease, although th.ey are occasionally ob- served in other affections. Dropsical swelling of the feet and lower limbs is a symptom be- longing to a late period of the disease. It is a remarkable fact that the mental faculties usu- ally remain intact, with the exception that the effect of the disease upon the mind is such as often to impair the ability to appreciate the fact of the existence of a serious affection. Patients frequently, even when the disease is far advanced, entertain confident expectations of recovery. They may refuse to believe that there is any danger, and perhaps are forming plans which involve prolonged life and health when it is evident to all around them that they are on the verge of the grave. The du- ration of the disease in fatal cases is extremely variable. In some exceptional instances it runs a comparatively rapid course, ending in a few weeks. In such cases it has been called " gal- loping consumption." It rarely ends within a period of three months ; it is by no means un- common for it to extend to two or three years ; and it not very infrequently lasts from 10 to 20 years. The writer has known an instance in which the disease existed for 40 years, prov- ing fatal at the end of this period. The diag- nosis of consumption is now, with the aid of indications furnished by auscultation and per- cussion, made with facility and positiveness. It may be diagnosticated at an early period, before it has made much progress. More- over, the extent to which the lungs are affect- ed and the amount of lesion are determined with great precision. The symptoms belong- ing to the clinical history which are especially diagnostic, in addition to a persistent cough with more or less expectoration, are spitting of blood, stitch-like pains at the summit of the chest, irregularly recurring chills, a frequent pulse, rise of the temperature of the body, an increase of the number of respirations per minute, perspiration during sleep, febrile exa- cerbations or hectic paroxysms, and progressive emaciation. The signs obtained by auscultation and percussion are those which represent the morbid physical conditions incident to the dis- ease, namely, solidification of portions of the lungs, the presence of liquid in the air tubes, roughening of the pleural surfaces with lymph, and the existence of cavities. Certain compli- cations are significant as regards the diagno- sis, such as chronic laryngitis, giving rise to huskiness and not infrequently loss of voice; tuberculous ulcerations of the intestines, caus- ing persistent diarrhoea; perineal fistula, and chronic inflammation of the peritoneum. On the other hand, there are certain affections which appear to exert a protective influence against consumption. The disease is rarely developed in those who suffer from asthma, pulmonary emphysema, and the structural af- fections of the heart which produce notable disturbance of the circulation. Our knowl- edge of the causes of consumption is still ob- scure. The popular belief is that the disease is caused by "taking cold," that is, follows a bronchitis. The study of a large number of cases fails in furnishing support for this belief. It is quite certain that a cold, whenever it appears to enter into the causation, acts only as an exciting cause, and is not sufficient in itself to produce the disease. For does the disease often follow acute inflammation of the lungs or pneumonia. This statement also applies to pleurisy. Statistics have shown that those who have contracted chests are not in consequence more liable to become con- sumptive. A hereditary influence undoubtedly enters often into the causation, persons whose parents or grandparents have been tuberculous being more likely to die of consumption than others. Moreover, facts show that sometimes, when progenitors have not been tuberculous, there is an innate constitutional tendency to consumption. As an illustration of this state- ment, the following may be cited : Five chil- dren of parents who were living and well died with consumption on arriving at ages of from 22 to 24 ; they were all the children of these parents, and none of the progenitors of the lat- ter had been known to die with consumption. Here must have been a congenital tendency, and there is no evidence that this tendency was inherited. A predisposition relates to age. In the great majority of cases the disease is developed between the ages of 20 and 30 years ; no age, however, is exempt from a li- ability to it. Climate has a manifest influence. Consumption prevails much more in climates which are humid and subject to frequent alter- nations of cold and heat, than in those which are dry and uniformly either warm or cold. Prof. Bowditch has ascertained that in the state of Massachusetts cases of consumption are especially numerous in situations in which the atmosphere is rendered humid by streams or marshes. A high altitude affords protection against the disease. A French writer, Jac- coud, states that observations for 15 consecutive years warrant him in asserting that in Alpine situations elevated 4,000 feet tuberculosis is almost unknown; and Dr. Hjaltelin, who re- sides in Iceland, aifirms that the inhabitants of that country enjoy exemption from consump- tion. Statistics prove that the disease prevails especially among persons whose occupations involve a sedentary life and confinement within doors, such as clerks and printers. A conclu- sion to be deduced from what is known of the causation is, that causative agencies exert their influence by producing a constitutional deterioration, the essential nature of which ig unknown. This condition, when it constitutes a predisposition to consumption, is called the tuberculous diathesis, and when sufficient to give rise to the disease it is called the tubercu- lous cachexy. An interesting and important discovery bearing on the causation of tubercu- lous disease was made in France in 1865, by Villemin. He demonstrated by a series of ex-